We would like to visit YNP and Grand Teton the next summer with 2 kids (6 and 2) for 5-6 days. Our concern is our 2 yrs old boy (he will be almost 3). He is very active and can't seat in the carseat for long. Is it a good age to travel to YNP at all? What activities would you recommend? What places to visit and where to stay?